This invention relates generally to optical proximity apparatus, and related methods, for determining the proximity and angular orientation of a target surface, without actually contacting the surface, and, more particularly, to optical proximity apparatus and methods in which two or more beams of light are directed onto the surface at oblique angles relative to each other.
Apparatus of this kind are useful in many applications where surfaces must be precisely positioned and, in some instances, angularly oriented, without actually being contacted by the apparatus. Many examples of such optical proximity apparatus are found in various manufacturing industries, where products must be precisely oriented, for example, for machining, welding and painting, as well as many other manufacturing processes.
The apparatus frequently direct a number of separate beams of light onto the surface at oblique angles, and the surface's proximity and angular orientation relative to the apparatus is determined by detecting the points at which the separate beams impinge on it. In some of such applications, the separate beams are directed at the surface sequentially, so that it can be readily determined which of the light spots on the surface result from each beam. Although such apparatus are generally effective in detecting the surface's position, it is not believed to provide as precise a proximity and angular orientation determination as is possible in all applications. This is because the surface can sometimes move, even if only slightly, before the positions of all of the beam spots have been detected and analyzed.
Many apparatus of this kind also require the use of two-dimensional photodetectors capable of measuring the x-y coordinates of each spot of light. Although such apparatus are generally effective in detecting the positions of the light beam spots, the photodetectors and their associated circuitry are believed to be unduly expensive.
It should, therefore, be appreciated that there is a need for a more precise, yet simplified and less expensive apparatus and related method for optically monitoring the proximity and, in some instances, the angular orientation, of a surface. The present invention fulfills this need.